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Amphicarpic plants produce both above-ground and below-ground seeds. Because below-ground seeds are protected in the soil and may maintain viability when above-ground conditions are stressful, they were proposed as an adaptation to recolonize a site after disturbance. However, whether below-ground seeds are the main colonizers after a disturbance remains unknown. Our goal was to understand whether recolonization by an amphicarpic species after fire was accomplished primarily through germination of seeds produced above-ground or below-ground. We investigated Polygala lewtonii, an amphicarpic, perennial species endemic to fire-prone Florida sandhill and scrub, where fire kills plants but subsequently increases recruitment and population sizes. Polygala lewtonii produces three flower types: above-ground chasmogamous flowers and above-ground and below-ground cleistogamous flowers, with previous research demonstrating chasmogamous flowers produce a much greater proportion of seeds than cleistogamous flowers. We quantified outcrossing in seeds produced by chasmogamous flowers to determine whether it differed from the 100 % self-fertilized below-ground seeds. Approximately 25 % of seeds from chasmogamous flowers showed evidence of cross-pollination. Assuming that chasmogamous flowers produce the majority of the above-ground seeds, as was shown previously, this indicates it is possible to differentiate between germination by above-ground versus below-ground seeds in post-fire colonization. We next compared genetic diversity, admixture, inbreeding and population genetic structure pre- and post-fire. If fire promoted germination of chasmogamous seeds, heterozygosity and admixture would increase, and genetic structure and inbreeding would decrease. Instead, inbreeding and genetic structure increased and admixture decreased, suggesting that the below-ground selfed seeds (with limited dispersal ability) increased their contribution to the population after fire, possibly because fire reduced above-ground seed viability. Additionally, new alleles not found previously in range-wide analyses emerged from the seed bank post-fire. These results suggest that amphicarpy is a powerful adaptation to preserve genetic variation, maintain adaptive potential and promote rapid post-fire colonization., We examined the mating system’s response to fire in Polygala lewtonii, a species endemic to fire-prone Florida sandhill and scrub. Polygala lewtonii has three flower types: above-ground chasmogamous (open-pollinated) and cleistogamous (closed, obligately self-fertilizing) flowers and below-ground cleistogamous flowers, with fruits produced both above-ground and below-ground. We used a genetic approach to test whether post-fire recolonization was accomplished primarily through germination of above-ground or below-ground seed. The below-ground selfed seeds showed an increased contribution to the population and new alleles emerged from the seed bank post-fire. These results suggest that amphicarpy is an adaptation to promote rapid post-fire colonization and preserve genetic variation and adaptive potential.

Conservation genetics studies not only provide information about genetic diversity and genetic structure to inform conservation strategies, they can also help infer life history characteristics such as mating system, pollinator, and seed dispersal strategy of a plant species. Here, we investigated Geocarpon (Mononeuria minima; Caryophyllaceae), an extremely diminutive, poorly known plant species from the south-central U.S. that is threatened due to high habitat specificity and habitat loss. The goals of this study were to use genetic data to help understand the basic attributes of the biology of Geocarpon, including mating system and the spatial extent of gene flow, how genetic variation is partitioned within and among populations and across the landscape, and how to protect that genetic variation. Most Geocarpon populations are highly homozygous and genetically homogenous, indicating a predominantly selfing mating system. Although the species maintains some allelic diversity, the majority of genetic variation was partitioned among populations, even in groups separated by small geographic distances (≥ 0.5 km), indicating very localized seed dispersal (gravity or water). Because genetic variation is structured at a fine scale, to conserve the full range of genetic diversity it is necessary to protect a large proportion of the populations of the species; we recommend protection of as many currently unprotected sites as possible, particularly in areas of the geographic range where few populations are protected, combined with ex situ conservation seed banking in sites that cannot be protected. This study illustrates how life history characteristics, particularly mating system, strongly influence patterns of genetic structure and can have major effects on the strategy to conserve genetic variation in an endangered species.

Understanding genetic diversity and structure in a rare species is critical for prioritizing bothin situandex situconservation efforts. One such rare species isPhysaria filiformis(Brassicaceae), a threatened, winter annual plant species. The species has a naturally fragmented distribution, occupying three different soil types spread across four disjunct geographical locations in Missouri and Arkansas. The goals of this study were to understand: (1) whether factors associated with fragmentation and small population size (i.e., inbreeding, genetic drift or genetic bottlenecks) have reduced levels of genetic diversity, (2) how genetic variation is structured and which factors have influenced genetic structure, and (3) how much extant genetic variation ofP.filiformisis currently publicly protected and the implications for the development of conservation strategies to protect its genetic diversity. Using 16 microsatellite markers, we genotyped individuals from 20 populations ofP.filiformisfrom across its geographical range and one population ofPhysaria gracilisfor comparison and analyzed genetic diversity and structure. Populations ofP.filiformisshowed comparable levels of genetic diversity to its congener, except a single population in northwest Arkansas showed evidence of a genetic bottleneck and two populations in the Ouachita Mountains of Arkansas showed lower genetic variation, consistent with genetic drift. Populations showed isolation by distance, indicating that migration is geographically limited, and analyses of genetic structure grouped individuals into seven geographically structured genetic clusters, with geographic location/spatial separation showing a strong influence on genetic structure. At least one population is protected for all genetic clusters except one in north-central Arkansas, which should therefore be prioritized for protection. Populations in the Ouachita Mountains were genetically divergent from the rest ofP.filiformis; future morphological analyses are needed to identify whether it merits recognition as a new, extremely rare species.

Amphicarphic species produce both aboveground and belowground seeds; the belowground seeds have been proposed to be an adaptation to disturbed sites because they are protected belowground, enabling them to persist and recolonize a site after disturbance. However, it is unknown whether such seeds indeed serve as the main colonizers after a disturbance. The amphicarpic species Polygala lewtonii is endemic to fire-prone Florida sandhill and scrub and is among only a few species with three flower types (aboveground chasmogamous flowers and both above and belowground cleistogamous flowers). The goal of this study was to understand whether recolonization of sites by P. lewtonii was accomplished primarily through germination of belowground seed. First, we quantified the outcrossing rate in seeds produced by aboveground chasmogamous flowers to determine whether we could detect differences in colonization of between seeds produced aboveground vs. belowground. Approximately 25% of seeds from aboveground chasmogamous flowers showed evidence of cross pollination and the seeds showed greater heterozygosity and lower inbreeding coefficients than pure selfing, indicating that it is possible to differentiate between selfed and non-selfed seed types in postfire colonization. Second, we analyzed genetic diversity, inbreeding, and genetic structure of the populations before and after a prescribed fire. If heterozygosity and admixture increased, and spatial population genetic structure and inbreeding decreased, this would indicate that fire promoted germination of outcrossed seed from aboveground flowers. However, inbreeding increased and spatial genetic structure and admixture decreased after fire, suggesting that selfed seed produced by belowground flowers predominantly recolonized the site after fire. Thus, amphicarpy is a powerful adaptation to fire-maintained environments by producing seeds that are well suited to the range of conditions presented by a highly variable, disturbance prone habitat.

Extinction is the complete loss of a species, but the accuracy of that status depends on the overall information about the species. Dracaena umbraculifera was described in 1797 from a cultivated plant attributed to Mauritius, but repeated surveys failed to relocate it and it was categorized as Extinct on the IUCN Red List. However, several individuals labelled as D. umbraculifera grow in botanical gardens, suggesting that the species’ IUCN status may be inaccurate. The goal of this study was to understand (1) where D. umbraculifera originated, (2) which species are its close relatives, (3) whether it is extinct, and (4) the identity of the botanical garden accessions and whether they have conservation value. We sequenced a cpDNA region of Dracaena from Mauritius, botanical garden accessions labelled as D. umbraculifera, and individuals confirmed to be D. umbraculifera based on morphology, one of which is a living plant in a private garden. We included GenBank accessions of Dracaena from Madagascar and other locations and reconstructed the phylogeny using Bayesian and parsimony approaches. Phylogenies indicated that D. umbraculifera is more closely related to Dracaena reflexa from Madagascar than to Mauritian Dracaena. As anecdotal information indicated that the living D. umbraculifera originated from Madagascar, we conducted field expeditions there and located five wild populations; the species’ IUCN status should therefore be Critically Endangered because < 50 wild individuals remain. Although the identity of many botanical garden samples remains unresolved, this study highlights the importance of living collections for facilitating new discoveries and the importance of documenting and conserving the flora of Madagascar.

Polygala lewtonii is a federally endangered, amphicarpic plant with a mixed mating system and three types of flowers: (1) aboveground, chasmogamous flowers (i.e., open-pollinated; CH), (2) aboveground, cleistogamous flowers (i.e., closed, selfing; CL) and (3) CL flowers on belowground stems (amphicarpy). Aboveground seeds are ant-dispersed, whereas belowground seeds are spaced across the length of the rhizome. Here, we collected individuals of P. lewtonii at both range-wide and fine geographic scales and genotyped them at 11 microsatellite loci. We analyzed patterns of genetic diversity and structure to understand: (1) the predominant mating system (selfing or outcrossing), (2) the movement of pollen and seeds across the landscape, and (3) the optimal strategy to conserve the full range of genetic variation. P. lewtonii reproduces predominantly by selfing or bi-parental inbreeding, but reproduction occurred through each of the three flower types. Some individuals produced by selfing/inbreeding were tightly clustered spatially, and were likely produced either by belowground flowers or by aboveground flowers with limited seed dispersal. Other selfed/inbred individuals were spatially separated (maximum of 15 m), and were likely produced by aboveground flowers followed by seed dispersal by ants. Fine-scale patterns of genetic structure indicate that some gene flow is occurring among aboveground CH flowers but both pollen and outcrossed seeds are moving limited distances (maximum of 0.5 km). Because genetic variation is structured at a fine spatial scale, protecting many populations is necessary to fully conserve the genetic variation in P. lewtonii. Conservation seed banking, if accompanied by research on seed germination requirements, may also contribute to the effective protection of genetic variation in P. lewtonii.

A taxonomic revision of Ctenitis (C. Chr.) C. Chr. (Dryopteridaceae) from Africa and the Western Indian Ocean was carried out. Forty species are recognized, of which 12 are described as new, eight are transferred to Ctenitis from other genera, and one is elevated from variety to species and transferred from Aspidium Sw. to Ctenitis. These 21 nomenclatural novelties include C. analamazaotrensis (Rakotondr.) Hennequin & Rouhan (comb. nov.), C. brevipetiolulata Li Bing Zhang & Yi F. Duan (sp. nov.), C. bullescens Rouhan, Li Bing Zhang & Yi F. Duan (sp. nov.), C. cerea Li Bing Zhang & Yi F. Duan (sp. nov.), C. comorensis Li Bing Zhang & Yi F. Duan (sp. nov.), C. crinigera (C. Chr.) Hennequin & Rouhan (comb. nov.), C. decaryana (C. Chr.) Hennequin & Rouhan (comb. nov.), C. dentata Li Bing Zhang & Yi F. Duan (sp. nov.), C. fibrillosa (Baker) Li Bing Zhang & Yi F. Duan (comb. nov.), C. hispida (Kuhn) Li Bing Zhang & Yi F. Duan (comb. & stat. nov.), C. jouyana (Rakotondr.) Hennequin & Rouhan (comb. nov.), C. longivillosa Li Bing Zhang & Yi F. Duan (sp. nov.), C. marginalisora Li Bing Zhang & Yi F. Duan (sp. nov.), C. mayottensis Li Bing Zhang & Yi F. Duan (sp. nov.), C. multilobata Li Bing Zhang, Yi F. Duan & Rouhan (sp. nov.), C. reunionensis Hennequin, Li Bing Zhang & Yi F. Duan (sp. nov.), C. sieberiana (Kaulf.) Hennequin & Rouhan (comb. nov.), C. sparsa Li Bing Zhang & Yi F. Duan (sp. nov.), C. spekei (Baker) Li Bing Zhang & Yi F. Duan (comb. nov.), C. subcrenulata (Baker) Li Bing Zhang, Rouhan & Yi F. Duan (comb. nov.), and C. tardieu-blotiae Li Bing Zhang & Yi F. Duan (sp. nov.). A key to these species is provided; all species are described and illustrated; and information on their distribution and habitats is given. Twenty-three relevant species reported in the literature are excluded from the flora, and their taxonomy, distribution, and nomenclature are discussed. Seventeen related names are lectotypified or neotypified including Aspidium cirrhosum Schumach., A. crinitum (Poir.) Wall. var. hispida Kuhn, A. cyclochlamys Fee, A. nitidum Bory ex Willd., A. pauciflorum Kaulf., A. sulcatum Kaulf. ex Bory, C. anjenabensis Tardieu, Dryopteris blepharochlamys C. Chr., Gymnogramma subsimilis Hook., Nephrodium crinitum (Poir.) Desv. var. maritimum Cordem., N. magnum Baker, N. spekei Baker, N. welwitschii Baker, Phegopteris biformis Mett. ex Kuhn, P. bivestita Mett., Polypodium baronii Baker, and P. efulense Baker; type information of related 262 names is also given.

Summary Photorespiration raises cellular CO2 levels about 3-fold in leaves of C3–C4 intermediate Flaveria species. This was shown by using 14C-based fluxomics to determine the Rubisco in vivo carboxylation-to-oxygenation ratios., Formation of a photorespiration-based CO2-concentrating mechanism in C3–C4 intermediate plants is seen as a prerequisite for the evolution of C4 photosynthesis, but it is not known how efficient this mechanism is. Here, using in vivo Rubisco carboxylation-to-oxygenation ratios as a proxy to assess relative intraplastidial CO2 levels is suggested. Such ratios were determined for the C3–C4 intermediate species Flaveria pubescens compared with the closely related C3 plant F. cronquistii and the C4 plant F. trinervia. To this end, a model was developed to describe the major carbon fluxes and metabolite pools involved in photosynthetic–photorespiratory carbon metabolism and used quantitatively to evaluate the labelling kinetics during short-term 14CO2 incorporation. Our data suggest that the photorespiratory CO2 pump elevates the intraplastidial CO2 concentration about 3-fold in leaves of the C3–C4 intermediate species F. pubescens relative to the C3 species F. cronquistii.

Numerous plant species worldwide including some Palicourea (Rubiaceae), Tanaecium (Bignoniaceae), and Amorimia (Malpighiaceae) species in Brazil cause sudden death and are known to contain monofluoroacetate (MFA). Two species of Palicourea, Palicourea aenofusca and Palicourea marcgravii, cause sudden death and are reported to contain MFA while other Palicourea species are reported to cause sudden death in livestock and are suspected to contain MFA due to the similarity in clinical signs. Using an HPLC-APCI-MS method to detect MFA, herbarium specimens representing 46 Palicourea taxa were screened for the presence of MFA. Additionally we screened five Psychotria taxa that are closely related to Palicourea species. Ten species of Palicourea were identified that contained MFA, two previously reported and eight newly reported here; these are closely related to each other, though some other related species did not contain MFA.

A procedure is described for the invitro regeneration of whole plants of Flaveria cronquistii (C3 species) F. pubescens and F. chloraefolia (both C3-C4 intermediate species) using different concentrations of 6-benzylaminopurine and alpha-napnthalenic acid.

Summary Flaveria cronquistii is a C3 plant and exhibits a CO2 compensation concentration (Γ) value of about 61 μl l−1 CO2 at 21 % O2 and 25°C. This species was hybridized with F. palmeri, a C4 species (Γ -6 μ1l −1 CO2). The hybrid exhibits a significantly lower value of Γ (44 μl−1) than the C3 parent. The hybrid leaves possess a distinct layer of cells around the leaf veins but with only a few chloroplasts within them. Activities of C4 typical enzymes (PEPC, Asp-AT, Ala-AT, NAD-MDH and NADP-ME) in the hybrid were significantly higher than in F. cronquistii. After 5 s exposition to 14CO2 about 24 % of the total ethanol soluble activity was in aspartate plus malate. This hybrid was backcrossed with F. palmeri. The value of Γ in the backcross plant was 19 μll-1 CO2. The activities of PEPC, Asp-AT and NADP-ME were further enhanced in comparison to the single hybrid. After 5 s exposure to 14CO2 47.5 % of label was in the C4-compounds aspartate and malate. The leave veins possess a bundle sheath with more chloroplasts than in the single hybrid but less than in F. palmeri. It is concluded that in both the single hybrid and the backcross a limited C4 cycle is functioning and CO2 is assimilated directly and simultaneously through the C4 and C3 pathways. δ 13C values of the hybrids were in the range of the C3 parent.